Telephone system



1931- c. A. AQDERSON ,827,734

TELEPHONE SYSTEM Filed July 20, 1927 2 Shee ts-Sheet l IfiFeT-TTFfi-- Clarence Hfindersun PULL UP Oct. 20, 1931. c. A. ANDERSON 1,827,734

TELEPHONE SYSTEM Filed July 20. 1927 2 Sheets-Sheet 2 TWO-5TEP RELAY MARGINAL Patented 20, 1931 UNITED STATES PATENT OFFICE men A. simmer, 01 CHICAGO, ILLINOIS, ABSIGNOR, BY IESNE ASSIGNMENTS, TO mamas ELECTRIC OOIPANY, INC OF CHICAGO, ILLINOIS, A CORPORATION O! DELAWARE TELEPHONE SYSTEM Application ma July 20; 1927. Serial m. 207,181.

The present invention relates to telephone systems in general, but more particularly to telephone stems employing call indicators for indicating to an operator the destina- 1 tion of calls.

The present invention discloses novel sending means and novel receiving meansfor sending and receiving impulses corresponding to desired telephone numbers and for ID displaying these numbers before an operator, an has been applied 'to a telephone system wherein one or more trunk lines connect two telephone exchanges.

An object of the invention is the produc- 1 tion of new and improved circuit arrangements whereby codes of impulses of different strength and polarities may be. transmitted upon the depression of a digit key corresponding to a digit desired to be sent over'a telephone line,

Another object of the invention is the production of new and improved relay arrangements in connection with the keys at the transmittin end of the circuit whereby a a plurality o impulses may be sent out upon a single operation of a key, and whereby a suflicient space is provided between successive impulses to rmit a switchin operation to be accomp ed at the receiving end of the circuit. I

Another object of the invention is the production of new and im roved arrangements at the receiv' end 0? a telephone line to enable a reduction t'obe made in the number of spring contacts on the register rela s in the receiver by arranging the receivin amp banks in interconnected squares and y applying one potential to a vertical conductor of an inte square-and another potential to a horiz'ont'al conductor to l" t the particular lamp common to both con uctors. Another of the invention has to do with a reduction in the number of receiving relays required by suitably arranging a single relay to carry the spring contacts ordinaril carried by two relays and. to cause the relay"to differentiate between which of the two functions it is to perform by arranging it to operate through one step or through two steps as the occasion demands.

Another object of the invention is the production of a new and improved arrangement for o crating the transfer relays used to trans er the receiving conductors from one set of receiving circuits to another as the code impulses are received.

There are other objects and features of the invention having to do more or less with the circuit details involved in carrying out the foregoing. The various objects and features of the invention can be understood best from a further perusal of the specification in connection with the accompanying drawm eferring now to the accompanying drawingscomprlsing Figs. l3, Fi s. 1 and 2 are circuit diagrams showing a su cient amount of apparatus involved in a telephone system embodying the features of the invention to enable the invention to be understood, and Fig. 3 is a table showing the code according to which the impulses are transmitted and indicating the rela s which respond to the various transmitt impulses.

Fi 1 shows the outgoing end of a trunk line tween two exchanges, together with the sending keys and the associated equipment.

Fig. 2 shows the incoming end of the trunk line in the second excha e including the various receiving relays an lamp sets.

Referring particularly to Fig. 3, which indicates the response of the receiving rela s A1C1, A2-C2, and A3-C3, Fig. 2, it will be noted that the digit 1, for example, is represented by a positive impulse and a negative impulse. Similarly, the digit 2 is represented by positive impulse and a negative impulse, but, as indicated by the fact that the positive sign of the digit 2 is made heavier than the positive sign of the digit 1, the positive impulse of the digit 1 is light, while the positive impulse of the digit 2 is heavy.

Similarly, a positive impulse and a negative impulse represent the digit 3, but in this case both impulses are heavy. The distinction between heavy impulses and light impulses is made according to whether a resistance, such as the resistances 21 and 22, Fig. 1, is included in the impulsing circuit at the time the impulse is sent. A positive impulse,

it may be pointed out, is one sent from the positive battery 24, while a negative impulse is one set from the negative battery 23.

Still referring to Fig. 3, it will be noted that the relay A of the connected set is 0perated in response to the positive impulse of the digit 1, but it'will be noted that no relay is operated in response to-the negative impulse. The reason for this will appear subsequently. It will be noted further that relays A and C respond in the connected set when the heavy positive impulse of the digit 2 is transmitted. .It may be pointed out that the reference character C is used to indicate that relay C of the connected set operates through its first step. The same response of the relays A andC occurs when the heavy positive impulse of the digit 3 is transmit-- ted, and relay C2 responds to the heavy negative impulse of the digit 3. The reference character C2 is meant to indicate that relay C of the connected set operates through its second step.

The invention having been discussed ingene-ral a detailed description will now be given. For this purpose it will be assumed that the operator in the firstexchange receives a call for a connection to be extended to a line terminating in the second exchange. In order to extend the connection, the operator'in the first exchange inserts the plug of a cord circuit .inner left-hand contacts of the k y through the contacts of relay 11. At the outer righthand contacts of the key K9, a circuit is closed for relay 19. Relays 19, as well as relay 20, is slightly slow to operate due to a stiff spring adjustment and due to a copper collar on the armature end of the core.

After a light interval of time has elapsed (suflicient to allow a full impulse to be transmitted), relay 19 operates and terminates the heavy negative impulse by disconnecting con-- ductor 26 from the heavy negative'impulse conductor extending up from the battery 23. Relay 19 also closes a circuit for the auxiliary relay 20. After an interval sufliciently long to permit switching operations hereinafter described to take place, the slightly slow-tooperate relay 8 operates and places a heav positive impulse on conductor 26 through the outer left-hand contacts of the depressedkey K9.

After having held the key K9 depressed for a sufiicient interval,.the operator releases the key, thereb terminating the heav positive impulse an -opening the circuit 0 relays 19 and 20. .These relays fallback quickly dueto their stifi' spring adjustment. When the operator depresses the key K10 to transmit the digit 0, two light negative impulses are transmitted through the .battery 23and the resistance 21, relays 20'and 19 operating as above described.

When the operator depresses the key K4 to transmit the digit 4, two light positive impulses are transmitted from the battery 24 through the resistance 22 by the action of the relays 20 and 19.

After the operator has finished transmitting the codeimpulses, the keys are all in; the position shown and the trunk line comprising conductors 25 and 26 is clear for voice-current transmission.

Referring now to Fig. 2, when the heavy negative impulse of the digit 9 passes through thereceiving relays51-53, the marginal relay 53 and relay 52 are operated, but the positively polarized relay-51 is not operated by the negative impulse. When the marginal relay 53 is operated, a circuit is closed for relay G1 through the lower armature of relay 55 and. the resistance associated with relay 01. When operated through the associated resistance, relay C1 operates throughits first step only, operating its lefthand armatures. At its inner left hand armature, relay C1 closes a locking c1rcu1t for itself through the associated resistance,

and at its outer left hand armature it removes ground from the vertical conductor common:

to the lamps 1, 4, and 7 and places ground on the conductor common to the lamps 2, 5 and 8 throughv the right hand armature of the relay, which armature shifts only when the relay is operated through its second step- When the relay 52 responds to the impulse it opens the circuit of the upper winding of the differential relay 55 and connects the upper winding of relay 55 in multiple with the winding of the auxiliary relay 54. Relay 55 now energizes through its lower winding .from ground on the locking conductor through the release button RB. Relay. 55 is adjusted so that its inner upper armature is very sensitive and operates first. Theremaining armatures of the rela are rather stiffly adjusted with the result that the relay hesitates for an appreciable length of time before operating further after the lightly adjusted inner upper armature has operated.-

When this armature operates, it disconnects the operating conductor from the upper winding of relay 55 and connects it to ground y through the adjacent upper armature, which as is noted on the'drawings breaks contact 'last, that is, after all other armatures of the relay have rated. During the interval required for t e relay to complete its opera- 7 tion afterthe inner upper armature has shifted, as above described, relay 54 1S operated from ground on conductor 75 through the operated contacts of relay 52. When relay 54 operates it locks itself operated by lacing a multiple ground connectlon on conductor 75 so that it will remain o erated and maintain conductor 75 the impulse endures an operated.

When relay 55 has operated fully, it breaks the ground connection (at its break-last contacts) from the extension of operating conductor 75, which would allow the current to cease flowing in the upper winding of the differential relay 56 if it were not for the multiple ground connection on conductor 75 at the auxiliary relay 54. Relay 52 falls back at the end of the impulse, as does the marginal relay 53 and opens the circuit of relay 54, at the same time replacing the normal ground connection on conductor 75. Relay 54 now falls back, leaving conductor 75 ounde as long as i maintains relay 52 grounded only at the normal contacts of relay 52. This ground potential on conductor 75 maintains the differential relay 56 nonoperated.

- As a further result of the operation of relay 55, it transfers the relay-operating circuit controlled by the mar inal relay 53 from the circuit of relay 01, through the associated resistance, throu h the lower armature of relay 56 to the win ing of relay C1 direct. Relay 55 also makes a similar transfer of the relay operating conductors controlled by the polarized relay 51 from relay A1 to relay B1 through the upper contacts of relay 56. At its u per armature, relay 55 closes a circuit for t e O lamp through contacts of the nonoperated relays A1 and B1. As a result the 0 lam is lighted unless one or the other of the reliiys -A1 and B1 is operated, as will now take place.

When the heavy positive impulse of the digit 9 is received by the receiving relays, all three relays operate. The marginal relay 53 closes a circuit through the lower armature, operated, of relay 55 and through the lower armature, normal, of relay 56 for the relay C1 independent of the associated resistance. As a result, relay C1 operates through its second step, and remains operated through its second step even after this circuit is opened, owing to the fact that the current flow through the associated resistance and through the locking contacts of the relay is suflicient to maintain the relay completely operated after it has once been operated fully. The right-hand armature of relay C1 transfers the ground potential from the vertical conductor common to the lamps 2, 5 and 8 to the vertical conductor common to the lamps 3, 6 and 9.

When the positively polarized relay 51 o erates, it closes a circuit thru the correspon ing armature, operated, of relay 55 and through the upper armature, normal, of relay 56 for the left-hand winding of relay B1. Relay'Bl o crates and locks itself to the associated loc ing conductor and atits lefthand armature it opens the circuit of the 0 lamp, and places battery throu h the inner? armature, normal, of relay 8 on t e horizontal conductor common to the lamps 7, 8 and 9. After this, the full potential is across the terminals of the lamp 9, and this lamp is lighted. An examination will show that When the transfer control relay 52 responds, it removes ground from conductor 75 and connects this conductor to the auxiliary relay 54. As a result, relay 56 0perates in the same manner as described in connection with relay 55 and transfers conductor 75 to relay 57. The auxiliary relay 54, as before, maintains conductor 7 5 grounded as long as relay 52 remains operated, so as to prevent the next relay in the transfer chain from operatin prematurely. The operating circuits contro led by the receiving relays are now transferred through contacts of relay 57 to the tens register.

When the first light negative impulse of the digit 0 is received, receiving relay 52 alone respgnds, relay 53 being marginal and relay 51 ing positively polarized.

Upon res onding, relay 52 aided by the auxiliary re ay 54, brings about the operation of relay 57, whereupon the operating circuits are transferred to relay 58. A circuit is closed for the 0 lamp of the tens set at the upper contacts of relay 57, whereupon the 0 lamp becomes lighted.

When the second light negative impulse of thedigit O is received, receiving relay 52 responds alone and brings about the operation of the transfer relay 58, whereupon the operating circuits are transferred to relay 59. As none of the relays A2C2 are operated the lamp 0 is lighted alone and the 18.1%? 1-9 are not lighted.

en the first light positive impulse of the digit 4 isreceived, relays 52 and 51 both res ond, and relay 51 closes a circuit throu h t e associated contacts of relays 54-59forthe left hand winding of relay A3. Relay A3 operates and closes a locking circuit for itself at its right hand armature, and at its outer tacts. The

left-hand armature it removes battery from the lower terminal of the 0 lamp and places battery on the horizontal conductor common to the lamps 1, 2, and 3. Relay 59 responds in the hereinbefore described manner to the op; eration of the-transfer control rela 52. r

When the second 1i ht ositive 1m ulse of the digit 4 is receive re ays 51 an 52 re spond as before, and rela 51 closes at this tlme a circuit through t e associated contacts of rela s 5460 for the left-hand winding of rela 3. Relay B3 operates and locks itself, at t e same time transferring the battery potential from the'horizontal conductor common to lamps 1, 2 and 3 to the conductor common to the lamps 4, 5 and 6. Relay 60 responds to the operation ofrelay 52 and disconnects the operating conductors from the windings of the relays B3 and C3. Since battery is now placed throu h the contacts of the operated relays A3 and 3 on the horizontal conductor common to lamps 4, 5, and 6, and, since relay C3, being non-operated, permits the ground potential to remain on the conductor common to lamps 1, 4, and 7 the lamp 4 alone is lighted.

As a result of the foregoing operations, the ninth lamp in the hundreds set, the tenth 'lamp in the tens set, and the fourth lamp in the units set are lighted to display to the operator the desired number 904. The operator in this exchange may now insert the plug of a cord circuit into the jack J2 and complete the desired connection.

After the "operator has noted the desired number, she'releases the operated equipment by momentarily operating the release button RB, whereupon the loc ed up relays fall back, extinguishing the lighted lamps and restoring the circuits to normal.

When the conversation is terminated, as may be discovered by the operator inthe originating exchange by listening in in the usual manner, the originating operator may transmit a disconnect number over the exchange trunk line comprising conductors 25 and 26. Thisdisconnect number may be some arbitrary number such as, for example, 111, or perhaps 000.

Upon perceiving the disconnect number transmitted over the intcrexchange trunk line by the operator in the first exchange, the cp-. era-tor in the second exchange may release the indicating equipment and take down the connection. The connection in the first exchange is taken down by the operator therein.

From the foregoing description, it will be obvious how the other digits are transmitted when desired.

It will be apparent that relay C1 may be replaced, if desired, by two relays, each relay carrying locking contacts, one relay carrying the first-step switching contacts and the other relay carryin v the second step switching con- {irst relay would, of course, be

operated over the conductor connected tothe back-contact of the lower armature of relay 55, and the second relay would, of course, be

connected to the conductor extending from the back contact of the lower armature ofrela 56. \The same arrangement may be apgried to the relays C2 and C3.

hat is claimed is v 1. In an impulse receiving device, a. chain of differential transfer relays, a transfer-colitrolrelay, an auxiliary relay, means responsive to an operation of the transfer-control relay for bringing about the operation of the first differential relay a circuit for said auxiliary relay controlled ointly by said transfercontrol relay and any connected one of the differential relays, and circuit arrangements I controlled by the auxiliary rela for preventing the operation of the next ifierential relay until the transfer-control relay has released and has reoperated.

2. In a relay register, a plurality of indi cating devices, vertical and horizontal conductors interconnecting said devices, each conductor being common to a separate plurality of said devices, relay contacts for placmg a given potential on any one of the vertical common conductors, and relay contacts for placing a different potential on any one of the horizontal conductors, whereby an effective current flow is produced through only one of said indicating devices.

3. Ina relay register a two step relay arranged to be operated through its first step or through its second step to register either of two different conditions, and a locking circuit for said rela effective to maintain the relay in either of 1ts two operated steps.

4. In combination, an impulse transmitter arranged to transmit digit-indicating impulse combinations in accordance with a code containing impulses of two polarities, with two strengths of impulse for each polarity, and two impulses per digit, and an impulse receiver and indicator arranged to respond to the impulses transmitted b said impulse transmitter in accordance with said code to indicate the digits transmitted.

5. In an impulse transmitting and receiving system, an impulse transmitter arranged to transmit a plurality of impulses, any 1mpulse to be of either positive or negative polarity and of either light or heavy strength, and an impulse receiver for receiving and indicating the received im ulses, the indication being different depen ing upon whether a received impulseis of one polarity or the other, and also upon Whether it is of heavy or light strength.

6. In an impulse transmitting and receiving system, means for transmitting impulses characterized both by their polarity and by their strength, and a receiving device for re ceiving the transmitted impulses comprising a polarized relay responsive to impulses of a thereat to transmit impnises in accordance with the digits in desired telephone numbers, and a visual indicating receiver at the second switchboard permanently connected to said line and arranged to be controlled thereover by the impulses sent out by said transmitter to indicate to the operator at the second' switchboard to where the connections are to be set up, said transmitter being arranged so that the voice currents do not flow through it during conversation, and tie receiving device being so designed that the dew of voice current through it during conversation is reiativeiy smaii.

8. In a telephone system, two exchanges, a trunk line extending from a mannai switchboard in the first exchan e to a, manuai switchboard the second exchange, a digit receiver and. indicator the nianuai switchboard in second exchange permanentiy connected to trunk line, and means un-= der the controi of the operator at the mannai switchboard in the first exchange for operating the receiver and indicator over said trunk iine to indicate the respective numbers of lines to which connections are to be set up over the trunk line from the first switchboard to the second switchboard.

9. In a teliephonesystem, two exchanges, a trunk line extending from a manual switch board in the first exchange to a manuai switchboard in the second exchange, a digit receiver and indicator at the manual switchboard in the second exchange permanentiy connected to said trunk line, means under the control of the operator at the manual switchboard in the first exchange for operating the receiver and indicator over said trunk line to indicate the respective numbers of lines to which connections are to be set up over the trunh line from the first switchboard to the second switchboard, means under the control of the operator at the second switchboard for restoring the receiver and indicator, said means under the control of the operator in the first exchange being again effective for operating the receiver and indicator over said trunk line to indicate to the operator at the second switchboard when the established connection is to be taken down.

10. In combination, means for transmitting and means for receiving the digits of a number in accordance with a'code comprising four characters arranged in ten combinations, each combination including two and only two of said characters.

11. In a telephone system, a trunk line connecting two exchanges, a transmitter in one exchange arranged to transmit four kinds of impulses over said trunk line, a re.- ceiver in the other exchange arranged to receive the four kinds of impulses over said trunk line and to distinguish between them, said transmitter and receiver being arranged to transmit and receive the impulses in ten different combinations, each combination including two and only two of said impulses.

12. In a telephone system, a trunk line connecting two exchanges, a transmitter in one exchange arranged to transmit four kinds of impulses over said trunk line, a receiver in the other exchange arranged to receive the four kinds of impulses over said trunk line and to distinguish between them, said trans- Initter and receiver being arranged to transmit and receive the impulses in ten different combinations, each combination including the same number of impulses as any other combination.

in witness whereof, I hereunto subscribe my name this 15th day of July, A. D. 192?,

CLARENCE A. ANDERSUN.

TIER 4 00 

